PostgreSQL
In this tutorial we will be creating alias for columns and tables in PostgreSQL.
We use alias to give new temporary name to columns and tables. Alias remains till the query executes.
This tutorial uses the employee table. To learn how to create a table check out this tutorial PostgreSQL - CREATE Table.
Do also read PostgreSQL - Select using WHERE clause tutorial on how to select rows from tables using filters.
SELECT * FROM employee; employeeId | firstName | lastName | score | lastModifiedAt | createdAt | birthday | email ------------+-----------+----------+-------+---------------------+---------------------+------------+---------------------- e01 | Yusuf | Shakeel | 0 | 2018-02-04 06:08:10 | 2021-01-01 01:01:01 | 1900-01-01 | yusuf@example.com e04 | Tin | Tin | 7 | 2018-02-04 06:08:10 | 2018-01-01 01:02:03 | 1900-10-20 | tintin@example.com e05 | Bob | Coder | 7 | 2018-02-04 06:08:10 | 2018-01-01 01:02:10 | 1900-08-20 | bobcoder@example.com e02 | John | Doe | 9 | 2018-02-04 06:08:10 | 2018-01-01 01:01:04 | 1900-02-03 | johndoe@example.com e03 | Jane | Doe | 9 | 2018-02-04 06:08:10 | 2018-01-01 01:01:04 | 1900-05-20 | janedoe@example.com (5 rows)
SELECT column_name AS alias_name FROM table_name;
In the following example we are going to give an alias id to the column employeeId of the employee table.
id
employeeId
employee
SELECT "employeeId" AS id, "firstName", "lastName" FROM employee; id | firstName | lastName -----+-----------+---------- e01 | Yusuf | Shakeel e04 | Tin | Tin e05 | Bob | Coder e02 | John | Doe e03 | Jane | Doe (5 rows)
SELECT tbl.column_name FROM table_name tbl;
In the following example we are going to give the employee table an alias e.
e
SELECT e."employeeId", e."firstName", e."lastName" FROM employee e; employeeId | firstName | lastName ------------+-----------+---------- e01 | Yusuf | Shakeel e04 | Tin | Tin e05 | Bob | Coder e02 | John | Doe e03 | Jane | Doe (5 rows)